System and method for controlling sand production in wells

ABSTRACT

A technique is provided for controlling sand in a well. The technique may utilize a vent screen assembly having a main screen, a vent screen, and a tubular member extending from the main screen to the vent screen. An expandable element is positioned around the tubular member between the main screen and the vent screen. After the vent screen assembly is deployed into a wellbore, a gravel pack can be formed around at least the main screen. The expandable element is selectively expanded in a radial direction to secure the gravel pack and to enable higher production rates.

BACKGROUND

In a variety of well applications, sand control systems and devices are used to limit the amount of particulates in a produced fluid, such as a hydrocarbon based fluid. Sand control equipment can be used in both production wells and injection wells and may comprise a variety of screens and/or gravel packs. In some applications, the production of sand in a given well can increase, or the existing sand control equipment can wear out or become otherwise ineffectual. Sand control equipment is then installed in the pre-existing well.

One technique for implementing sand control in pre-existing wells involves the use of vent screen equipment. Vent screen equipment is deployed into a well, and gravel is pumped around the outside of the equipment using standard gravel packing procedures. Production fluid is then allowed to flow from the surrounding formation, through the gravel pack, and through the vent screen equipment for production to a desired collection location. However, production flow rates into the vent screen equipment must be maintained at a substantially low rate to prevent the unloading of gravel from the gravel pack positioned in the annulus.

SUMMARY

In general, a vent screen assembly is prepared with a main screen, a vent screen, and a tubular member extending from the main screen to the vent screen. The vent screen assembly may also comprise an expandable element positioned around the tubular member between the main screen and the vent screen. In some embodiments, when the vent screen assembly is deployed into a wellbore, a gravel pack can be formed around at least the main screen. The expandable element may be selectively expanded in a radial direction to secure the gravel pack and enable higher production rates.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

FIG. 1 is a front elevation view of a sand control and production system deployed in a wellbore;

FIG. 2 is a front elevation view of a vent screen assembly positioned in a wellbore with an expandable element in a radially contracted position;

FIG. 3 is a front elevation view of a vent screen assembly positioned in a wellbore with the expandable element in a radially expanded position;

FIG. 4 is a front elevation view of an alternate vent screen assembly positioned in a wellbore; and

FIG. 5 is a front elevation view of another alternate vent screen assembly positioned in a wellbore.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The systems and methods disclosed herein generally comprise a vent screen assembly that may be positioned in a pre-existing wellbore and surrounded with a gravel pack. The gravel pack is used to remove particulates from inflowing production fluid, such as hydrocarbon fluid from a surrounding hydrocarbon bearing formation. The vent screen assembly further comprises an expandable element that can be expanded in the downhole position to secure the gravel pack and enable higher production fluid flow rates. The expandable element can be designed to expand radially outward toward a surrounding wellbore wall without requiring an additional trip downhole to actuate the expandable element. In one embodiment, the expandable element comprises a swellable packing element that swells in the presence of specific fluids, such as naturally occurring wellbore fluids or fluids directed downhole.

The swellable material used to form the swellable packing element can be designed to swell in different fluids depending on the well type. In some embodiments, the swellable packing element is designed to swell outwardly toward a wellbore wall, e.g., wellbore casing, until the entire annulus is completely filled. This approach enables much higher production fluid flow rates and also allows for the use of a relatively short tubular member extending between a main screen and a vent screen of the vent screen assembly, as described in greater detail below. In other embodiments, the swellable packing element is designed to swell only part of the distance toward the surrounding wellbore wall. For example, the gravel pack and the swellable packing element can be designed such that the swellable packing element expands against the gravel. The stress acting against the gravel in the annulus greatly reduces the mobility of the gravel and thus also facilitates increased production fluid flow rates from the well. Other types of materials and mechanisms also can be used to radially expand the expandable element in a manner that secures the gravel pack to accommodate higher production fluid flow rates.

Referring generally to FIG. 1, a well system 20 is illustrated as deployed in a wellbore 22 according to one embodiment of the present invention. The wellbore 22 is illustrated as extending downwardly to a subterranean formation 24, e.g., a hydrocarbon reservoir, from a wellhead 26 positioned at a surface location 28. The well system 20 can be utilized in a variety of wells having generally vertical or deviated wellbores. As illustrated, wellbore 22 is defined by a surrounding wellbore wall 30 that may be an open wellbore wall, a casing, or a combination of cased and open sections. As illustrated, wellbore wall 30 may be defined by a casing 32 having perforations 34 that allow communication between wellbore 22 and the surrounding formation 24. For example, a production fluid, e.g. a hydrocarbon based fluid, can flow from formation 24, through perforations 34, and into wellbore 22.

In FIG. 1, a vent screen assembly 36 is illustrated as deployed in wellbore 22 proximate formation 24. The vent screen assembly 36 generally comprises a main screen 38, a vent screen 40, and an expandable element 42 positioned between main screen 38 and vent screen 40. In this example, a gravel pack 44 has been formed around main screen 38 and fills the annulus between main screen 38 and the surrounding wellbore wall 30. The gravel pack 44 can be placed in a normal gravel pack mode at or below fracturing pressure with various types of treatment fluids. Alternatively, the gravel pack 44 can be placed as part of a frac pack in which hydraulic fracture is created using one or more treatment fluids, and the gravel is placed both in the fractures and in the annulus surrounding at least a portion of vent screen assembly 36. The gravel pack 44 can be formed with a variety of equipment and according to a variety of procedures used for gravel packing operations.

As illustrated, the expandable element 42 is expanded against wellbore wall 30 to secure gravel pack 44. The expansion of expandable element 42 can be accomplished automatically without requiring an additional trip downhole to initiate the expansion. Once element 42 is expanded, gravel pack 44 becomes secured and a high rate of production fluid flow can be conducted through vent screen assembly 36. As illustrated by arrows 46, the production fluid flows from formation 24, through gravel pack 44 and into main screen 38. From main screen 38, the production fluid flows upwardly to vent screen 40 and exits vent screen 40 for production to a desired collection location, such as a surface location.

Production of fluid from wellbore 22 can be accomplished according to several types of equipment and procedures. For example, artificial lift mechanisms can be used to produce hydrocarbon based fluids to the surface. As illustrated in the example of FIG. 1, production of fluid expelled from vent screen 40 can be accomplished by deploying a production string 48 downhole into wellbore 22. Production string 48 may comprise, for example, an artificial lift system 50 moved downhole on a conveyance 52. In this example, conveyance 52 comprises tubing, e.g. coiled tubing, however other types of conveyances can be employed. The production string 48 also may include or cooperate with one or more packers 54 positioned to isolate a specific production zone or zones along wellbore 22. By way of example, artificial lift system 50 may comprise an electric submersible pumping system that can be operated to draw in production fluid from vent screen assembly 36 and to produce that fluid upwardly to a desired location.

Referring generally to FIG. 2, one embodiment of vent screen assembly 36 is illustrated in greater detail. In this embodiment, main screen 38 is a lower screen positioned below vent screen 40. Both main screen 38 and vent screen 40 are coupled to a tubular member 56, and expandable element 42 is disposed around tubular member 56 between main screen 38 and vent screen 40. In FIG. 2, the expandable element 42 is in a radially contracted state to enable, for example, movement of vent screen assembly 36 to a desired location within wellbore 22, e.g. a production zone in a pre-existing wellbore requiring sand control.

Once vent screen assembly 36 is positioned at the desired location within wellbore 22, a gravel packing procedure can be carried out to place a packing material 58, e.g., gravel, in the annulus around at least main screen 38, as illustrated in FIG. 3. The packing material 58 forms gravel pack 44 which serves to filter fluid flowing into wellbore 22 from formation 24. After gravel pack 44 is formed, expandable element 42 is expanded in a radially outward direction toward wellbore wall 30 to secure packing material 58 as a contained gravel pack 44. In the embodiment illustrated in FIG. 3, the expandable element 42 expands outwardly through the entire annulus and into engagement with the surrounding wellbore wall 30.

By way of example, expandable element 42 may comprise a swellable packing element formed of a swellable material 60. The swellable material 60 swells upon exposure to a specific fluid and expands toward surrounding wellbore wall 30. The swellable packing element can be contained and directed by a variety of mechanisms or simply through the configuration of vent screen assembly 36. For example, because of its position around tubular member 56 between main screen 38 and vent screen 40, the swelling of expandable element 42 causes the expandable element to enlarge toward wellbore wall 30 in a radially outward direction.

Another method of utilizing vent screen assembly 36 is illustrated in FIG. 4. In this embodiment, gravel pack 44 extends upwardly beyond main screen 38 and at least partially into the annulus surrounding expandable element 42 when the expandable element is in a contracted configuration. When expanded, expandable element 42 is able to expand only partially through the annulus toward surrounding wellbore wall 30 before engaging a portion 62 of gravel pack 44. However, the expansion of the expandable element 42 is able to place sufficient stress or pressure against gravel pack 44 to prevent or greatly reduced the potential for displacement of packing material 58 from the gravel pack 44. As a result, the flow rate of production fluid through gravel pack 44 and vent screen assembly 36 can be increased.

By way of example, the expandable element 42 illustrated in FIG. 4 can be formed from swellable material 60 to create a swellable packing element. The swellable material 60 can be selected to apply pressure against a surface of the gravel pack 44. However, a less rigid swellable material 60 also can be selected so that swelling of expandable element 42 causes swellable material 60 to penetrate the packing material 58, e.g., gravel, during the swelling process. Penetration of the gravel or other packing material further locks the gravel pack 44 in place. Accordingly, swellable material 60 can be formed from a variety of polymers, gels, and rubbers depending on the desired performance of swellable material 60 in pressing against the gravel pack or in actually penetrating the gravel pack.

Referring generally to FIG. 5, another embodiment of vent screen assembly 36 is illustrated. In this embodiment, the main screen 38 is positioned beneath swellable material 60 but the upper screen has been removed. In some applications, the upper screen can be removed to reduce the system cost and to potentially improve flow efficiency. With the embodiment illustrated in FIG. 5, the screen also can be re-entered for later remedial work.

Well system 20 can be formed with a variety of vent screen assemblies, production strings, and artificial lift systems. Additionally, the vent screen assembly can be deployed in many types of wells and in many types of environments to improve sand control. For example, the vent screen assembly is amenable to placement in pre-existing wells. A variety of packing procedures also can be employed with the use of conventional gravel or other packing materials.

The shape, size and materials used in constructing the main screen, tubular member, vent screen and expandable element of the vent screen assembly also can vary according to the well and the application for which the vent screen assembly is deployed downhole. For example, expandable element 42 may be formed from a variety of components and materials. As described above, the expandable element 42 and the overall vent screen assembly 36 can be formed to enable expansion in a wellbore without requiring an additional trip downhole. If the expandable element 42 comprises a swellable packing element, a variety of swellable materials can be used and those swellable materials can be selected to expand upon exposure to a desired fluid. For example, expansion of the swellable material can be initiated by specific fluids located downhole or by fluids directed downhole through wellbore 22 or production string 48.

Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims. 

1. A method of controlling sand in a well, comprising: preparing a vent screen assembly with a tubular member, a main screen connected to the to the tubular member, a vent screen connected to the tubular member, and an expandable element positioned around the tubular member between the main screen and the vent screen; deploying the vent screen assembly into a wellbore to a desired location; and expanding the expandable element toward a surrounding wellbore wall without requiring an additional trip downhole.
 2. The method as recited in claim 1, further comprising gravel packing around the main screen prior to expanding the expandable member.
 3. The method as recited in claim 1, wherein expanding comprises expanding a swellable packing element.
 4. The method as recited in claim 1, wherein expanding comprises expanding the expandable member against the surrounding wellbore wall.
 5. The method as recited in claim 1, wherein expanding comprises expanding the expandable member against a portion of a gravel pack disposed between the expandable member and the surrounding wellbore wall.
 6. The method as recited in claim 1, further comprising producing a fluid flowing from the vent screen.
 7. A system for use in a wellbore: a vent screen assembly having a tubular member, a main screen coupled to the tubular member, a vent screen coupled to the tubular member, and an expandable element positioned around the tubular member between the main s screen and the vent screen.
 8. The system as recited in claim 7, wherein the expandable element comprises a swellable material.
 9. The system as recited in claim 7, wherein the main screen is positioned below the vent screen to accommodate fluid flow into the main screen, up through the tubular member, and out through the vent screen when the vent screen assembly is positioned in a well.
 10. The system as recited in claim 7, further comprising a gravel pack positioned around the main screen.
 11. The system as recited in claim 7, wherein the expandable element swells when exposed to a well related fluid.
 12. A method, comprising: coupling a screen to a tubular member; forming a gravel pack around the screen in a wellbore; and positioning a radially expandable element around the tubular member and proximate the screen to secure the gravel pack.
 13. The method as recited in claim 12, wherein coupling comprises coupling a main screen to a vent screen with the tubular member.
 14. The method as recited in claim 13, wherein positioning comprises positioning a swellable material between the main screen and the vent screen.
 15. The method as recited in claim 12, further comprising expanding the radially expandable element.
 16. The method as recited in claim 15, wherein expanding comprises expanding the radially expandable element against a surrounding wellbore wall.
 17. The method as recited in claim 15, wherein expanding comprises expanding the radially expandable element into the gravel pack.
 18. A method, comprising: preparing a vent screen assembly with a main screen and a vent screen; and separating the vent screen from the main screen with a swellable material.
 19. The method as recited in claim 18, further comprising deploying the vent screen assembly into a wellbore.
 20. The method as recited in claim 19, further comprising gravel packing around the main screen.
 21. The method as recited in claim 20, further comprising expanding the swellable material radially outward while positioned between the vent screen and the main screen. 